Pour 2 cups of water into a pot and bring it to a boil over high heat. Once it's bubbling hard, remove from heat and let it cool for 2 minutes. You want it hot but not so scorching that it hurts to handle.

Pour the red gelatin package into your first mixing bowl. Add 2/3 cup of the hot water and stir for about 2 minutes until the powder completely dissolves. There shouldn't be any grainy bits floating around.

Stir in 1/3 cup of strawberry juice and 1/4 teaspoon vanilla extract into the red mixture. Divide this evenly between 6 clear cups (about 1/4 inch layer on the bottom). Refrigerate for exactly 20 minutes — not less, or it won't set enough to hold the next layer.

While the red layer chills, prepare your white gelatin the same way using hot water. Let it cool slightly, then stir in the remaining strawberry juice. Pour this as your middle layer into each cup when the red is set, then refrigerate for another 20 minutes.

Prepare the blue gelatin with hot water and cool it briefly. Mix in the blueberry juice and pour it as your final layer. Chill the entire assembled patriotic jello cups family for at least 2 hours until completely set and jiggly.

Top each cup with a dollop of whipped topping right before serving. Scatter the fresh strawberries and blueberries on top, add a tiny squeeze of lemon juice, and serve immediately. The texture stays perfect for up to 6 hours once you add the whipped cream topping.